Sea Trial Test Research Articles

수중모함에서 사출되는 고속 수중운동체의 초기 거동 모델링 및 시뮬레이션

ABSTRACT Heavy-weight high speed underwater vehicle(HSUV) is launched from the submerged mother ship. For the safety point of view, it is important to confirm whether the HSUV would touch the launching mother ship. In this paper, the hydrodynamic force and moment were modeled by the polynomials of motion variables and the simple lift and drag acting on a plate and cylinder which consist of the HSUV’s several parts. The mother ship was assumed as the Rankine half body to consider the flow field near the moving ship. Such hydrodynamic force and moment were included in the 6 DOF equations of motion of the HSUV and the dynamic simulations for the various conditions of the HSUV until the propeller activation were performed. Developed simulation program is expected to reduce the number of expensive sea trial test to develop safety logic of the HSUV at the initial firing stage.Key Words : High Speed Underwater Vehicle(고속 수중운동체), Modeling and Simulation(모델링 및 시뮬레이션), Initial Firing Stage(초기 발사단계), Dynamics(동력학)

해양환경에서 선박 추적을 위한 라이다를 이용한 궤적 초기화 및 표적 추적 필터

This paper describes the track initiation and target-tracking filter for ship tracking in a marine environment by using Light Detection And Ranging (LiDAR). LiDAR with three-dimensional scanning capability is more useful for target tracking in the short to medium range compared to RADAR. LiDAR has rotating multi-beams that return point clouds reflected from targets. Through preprocessing the cluster of the point cloud, the center point can be obtained from the cloud. Target tracking is carried out by using the center points of targets. The track of the target is initiated by investigating the normalized distance between the center points and connecting the points. The regular track obtained from the track initiation can be maintained by the target-tracking filter, which is commonly used in radar target tracking. The target-tracking filter is constructed to track a maneuvering target in a cluttered environment. The target-tracking algorithm including track initiation is experimentally evaluated in a sea-trial test with several boats.

Performance Measurement and Evaluation of a Marine Diesel Engine

It is significant that marine diesel engines should be run in accordance with factory or sea trial tests from the point of power and fuel consumption. It might not be possible to measure directly the power over the engine at the required load ranges. This is acceptable for both generator engine and main engine. In classical performance evaluation, compression pressure, maximum pressure, exhaust temperature and fuel pump index values are measured during operation. However, it is not possible to find the real reason of the fault in case of deterioration in the performance values. By solving the faults with palliative methods, far greater engine faults occurred in medium and long term due to the fact that the engine cannot be kept in high performance conditions. In this study, the parameters affecting the power and fuel consumption are evaluated by using p-V

Parametric study to identify the cause of high torsional vibration of the propulsion shaft in the ship

AbstractSince torsional vibration can lead to fatigue failure of the propulsion shaft in a ship, it should be restricted from the first step of the design through calculation and verified at the sea trial test step through measurement. Considering that the torsional vibration of the shaft is a system characteristic, it is strongly related to the vibration modes at the natural frequencies of the shaft. Therefore, the actual torsional vibration problem can occur due to the variation of parameters such as those of the vibration system, including mass of inertia, damping, and stiffness, which differ from the design.In this research, the root cause analysis of the high torsional vibration which occurred in the actual ship is described through a parametric study performed using numerical analysis. Parameters that can increase the torsional vibration of the propulsion shaft are selected, including coupling stiffness, shaft stiffness, coupling damping, and shaft damping. Through the torsional vibration calculations with variations of these parameters, the extent of the effect of these parameters on the torsional vibration of the propulsion shaft is investigated and the cause of the increased torsional vibration is identified.

France Energies Marines: objectives and status of the French sea-trial test sites

The development of Marine Renewable Energy (MRE) technologies requires the test of industrial scale prototypes in real conditions to validate their performance, reliability etc. prior to deploying commercial scale projects. MRE Test sites, the implementation of which was initiated in the UK with the EMEC in 2004, offer a pooled infrastructure to technology developers, hence sharing the cost of key infrastructure components over multiple devices, and a range of services aimed at supporting the developers in the various stages of technology development.In France, France Energies Marines, the research institute dedicated to MRE, is coordinating the development and operations of test sites offering the required infrastructure for wave energy, tidal current energy and floating offshore wind.The coordination of the various test sites at a national level offers a range of benefits to both the local partners involved in the development and operations of these sites and to the industrial developers with access to a large pool of highly skilled team, shared equipment and common policies and quality standards for example. France Energies Marines is also working to develop collaboration and cooperation at an international level with other test and research centres.

Design of a Fuel-Cell-Powered Catamaran-Type Unmanned Surface Vehicle

The goal of this study is to verify the applicability of fuel cells for powering surface vessels by developing a small catamaran-type unmanned surface vehicle (USV) powered by a hydrogen fuel cell. This study encompasses the entire process of designing a fuel-cell-powered USV, as well as sea trial tests with a 1.487-m full-scale prototype. To improve the performance and system efficiency of the USV, a simulation-based hull form design and integrated control systems were implemented during the design process. First, the optimum hull form of the catamaran, with the optimum separation, was determined based on hydrodynamic optimization using parametric models to achieve good fuel economy. Second, an automatic control system integrated with the global positioning and inertial navigation systems was implemented in the designed catamaran so that it had the ability to perform waypoint, departure, station keeping, and turning circle maneuvers. Next, the gain parameters of the fuzzy proportional-integral-derivative (PID) controller were adjusted to assure reliable tracking control. Automatically controlled trial tests were then conducted to validate the performance of the autonomous surface vehicle with respect to the fuel cell power requirements and its dynamic motion. Based on the results of the trial tests and the transient response of the fuel cell, a hybrid power control algorithm for the fuel cell and the batteries was implemented for more efficient power utilization. This catamaran-type unmanned surface vehicle powered with a fuel cell can be utilized for ocean environment monitoring and multifunctional missions.

실선시운전 선속 보정을 위한 실시간 해수유동 예측 활용

실선시운전 선속 보정을 위한 실시간 해수유동 예측 활용

1인승 소형 보트 설계 및 속도성능 분석

The objective of the This study is to access the speed performance employing the sea trial test and CFD with the our own designed and manufactured one-man boat. The overall design process including hull form design was explained. The sea trial was carried out with a manufactured boat in the clam sea. Brake power at the design speed of a boat through the sea trial was measured as 1680 W. The flow computation was conducted considering free surface and dynamic trim using a commercial CFD code(STAR-CCM+). The result of computation provided the information that residual resistance is bigger than fraction`s at design speed. The total efficiency were predicted based on the sea trial and CFD. The Total efficiency was divided into shaft efficiency and quasi-propulsive efficiency. By using quasi-propulsive efficiency, it becomes possible to predict speed performance of boat in future. The results can provide information regarding hull form design, performance analysis and development of a boat in future.

限界小翼面積プロペラの研究

This paper concerns results of model tests and full scale measurements of the propeller designed for inland ship (749 GT chemical tanker) aiming 1% increase of propulsive efficiency comparing with 1st retrofit small blade area NHV (Non Hub-Vortex)propeller.It was shown in the 1st report that the 1st retrofit propeller, of which blade area was decreased by 20% from the original propeller, reduced 4% of the engine output without any problem of the ship vibration and cavitation erosion.SBA-NHV propeller (Smallest Blade Area NHV propeller), of which the diameter was increased by 3.3% and the blade area was decreased by 10% from the 1st retrofit propeller, was designed and towing tank tests (propeller open water test and self propulsion test) and cavitation tests (cavitation observation, erosion paint test and fluctuating pressure measurement) were carried out. The model test results showed that the propulsive efficiency of the SBA-NHV propeller is about 1.5% higher than that of the 1st retrofit propeller and the risk of cavitation erosion and the fluctuating pressure of both propellers are almost equivalent.Finally, sea trial test of 749 GT chemical tanker was performed with the SBA-NHV propeller which was manufactured as the second retrofit propeller. The sea trial test results demonstrated about 2.5% deduction of engine output without any problem of the ship vibration comparing with the 1st retrofit propeller. And it was confirmed that the turning and stopping abilities of the SBA-NHV propeller were equivalent and a little worse respectively comparing with those of the original propeller.

FRP 복합재료 방향타 장착 근해어선의 해상시운전시험 결과분석

This paper reports the results of a comparative study on rudder performance between the steel rudders that have been used in coastal angling fishing boats in the 20-GT class and the newly developed FRP composite material rudders. In order to compare the rudder performances of these two types, a sea trial test was carried out to investigate the speed performance, fuel consumption, and ship's turning ability. The results showed that the sea trial performance of the FRP composite rudder was better than that of the steel rudder type in terms of the sea speed, fuel consumption rate, and turning ability.

Fuel-saving ship route using the Navy’s ensemble meteorological and oceanic forecasts

Fuel conservation and carbon reduction are important issues in current naval operations. Optimal ship route (i.e. minimum fuel consumption) depends on specific ship platform characteristics and near real-time environment such as weather, ocean waves, and ocean currents. The environmental impact of shipping can be measured on different spatial and temporal scales. As a vital component of the smart voyage planning (SVP) decision aid, the US Navy’s meteorological and oceanographic (METOC) forecast systems play an important role in optimal ship routing, which enables fuel savings in addition to the aid of heavy weather avoidance. This study assesses the impact of METOC ensemble forecast systems on optimal ship route. Tests of the SVP decision aid tool are also conducted for operational fleet use and concept of operations for the USS Princeton guided missile cruiser (CG)-59 in a sea trial test following the 2012 Rim of the Pacific exercises.

새로운 축기진력 계측시스템 및 모형 실험법 개발

New experimental devices and methods to measure shaft forces of ships are proposed in this paper. The strain gauge type six-component load cell was newly designed and installed to the end of the propeller shaft. The signals generated from the sensor in the propeller rotating are transferred to the new data amplifying and processing board on the shaft and the data is transmitted to the self-made wireless receiver. To find out the characteristics of shaft forces during port and starboard turning motions in sea trial, oblique and combined yaw maneuvering tests at straight, transient, maximum yaw rate, steady conditions were performed with the model ship installed the shaft forces measuring device using circular motion tester of Samsung Ship Model Basin. Characteristics of the measured shaft forces in model tests show quantitatively good agreement with the computed values obtained by the CFD programs using the measured wake data in oblique towing conditions. In the near future, It is hoped that the estimated shaft forces for a ship from this experimental method could be validated through comparison with directly measured values of a ship.

Hardware-In-the-Loop Simulation for Development of Fin Stabilizer

A ship cruising in the ocean oscillates continuously due to wave action. In order to reduce the ship's roll, we developed a fin stabilizer as an anti-rolling device for a 500-ton-class high-speed marine vessel. During the development phase, it was necessary to set up control gains for the motion and hydraulic systems and assess the effectiveness of the anti-rolling performance on the ground. For this reason, a Target Simulator, which simulated the ship's motion, was given operator inputs such as the engine telegraph and waterjet deflection angle, and generated roll using a one-degree-of-freedom motion base. Hardware-In-the-Loop Simulation (HILS) was performed using the Target Simulator in order to confirm the various logics of the developed fin stabilizer, select initial control gains, and estimate the anti-rolling performance. In conclusion, it was confirmed that HILS was very helpful to develop the fin stabilizer because it could reduce the number of sea trial tests that were needed and could find many malfunctions in the factory a priori.

限界小翼面積プロペラの研究

This paper concerns results of model tests and full scale measurements of the propeller designed for inland ship (749 GT chemical tanker) aiming 1% increase of propulsive efficiency comparing with 1st retrofit small blade area NHV (Non Hub-Vortex) propeller. It was shown in the 1st report that the 1st retrofit propeller, of which blade area was decreased by 20% from the original propeller, reduced 4% of the engine output without any problem of the ship vibration and cavitation erosion. SBA-NHV propeller (Smallest Blade Area NHV propeller), of which the diameter was increased by 3.3% and the blade area was decreased by 10% from the 1st retrofit propeller, was designed and towing tank tests (propeller open water test and self propulsion test) and cavitation tests (cavitation observation, erosion paint test and fluctuating pressure measurement) were carried out. The model test results showed that the propulsive efficiency of the SBA-NHV propeller is about 1.5% higher than that of the 1st retrofit propeller and the risk of cavitation erosion and the fluctuating pressure of both propellers are almost equivalent. Finally, sea trial test of 749 GT chemical tanker was performed with the SBA-NHV propeller which was manufactured as the second retrofit propeller. The sea trial test results demonstrated about 2.5% deduction of engine output without any problem of the ship vibration comparing with the 1st retrofit propeller. And it was confirmed that the turning and stopping abilities of the SBA-NHV propeller were equivalent and a little worse respectively comparing with those of the original propeller.

실선시운전시험을 통한 예부선의 조종 특성 연구

예선이 부선을 선미예인하고 있는 상황에서의 예부선 조종특성을 확인하기 위하여, 예선 단독 실선시운전과 예부선 통합 실선시운전 시험을 수행하였다. 속력시험, 가감속시험, 10도 선회시험, 20도 선회시험, 10도 지그재그시험, 20도 지그재그시험을 통하여 다양한 상황에서의 예선과 부선의 운항 특성을 확인하였다. 그 결과, 부선이 선미예인되는 경우, 예선의 전술선회직경은 예선 단독운항일 때보다 증가하며, 선수동요각 변화율이 낮음을 확인하였고, 침로 변경을 함에 있어 부선의 선수동요각 변화가 늦고, 오버슈트각이 큰 것을 확인하였다. 또한 선회나 침로 변경 시, 부선의 선회궤적이 예선의 선회궤적 안쪽에도 존재할 수 있음을 확인하였다. 따라서 부선을 선미예인하는 운항자는, 선회 및 침로변경 시 예부선의 선회궤적, 예부선의 선수동요각 변화시간 및 오버슈트각이 증가하는 것을 충분히 인지하고 운항해야 할 것으로 판단된다. In order to investigate the maneuverability of tug-barge, sea trial tests such as speed, acceleration/deceleration, <TEX>$10^{\circ}$</TEX> turning, <TEX>$20^{\circ}$</TEX> turning, <TEX>$10^{\circ}/10^{\circ}$</TEX> zigzag and <TEX>$20^{\circ}/20^{\circ}$</TEX> zigzag were conducted with both tug and tug-barge. From the result of turning test, longer tactical diameter and lower rate of turn of tug-barge than those of tug are obtained. From the result of the zigzag test, bigger overshoot angle of tug-barge than that of tug is obtained. When they turned or changed a course, it showed that the barge turned inner side of the trajectory of tug. For the safe navigation, the helmsman of tug-barge should be aware of these maneuvering characteristics.

빙두께 및 강도 보정기법을 이용한 모형시험결과의 실선시운전 적용연구

This paper deal with the validation of correction method of ice strength and thickness to the sea trial condition based on the ice model test results. It is very difficult to conduct the model test corresponding to the sea trial condition exactly. In addition, the available sea trial data is not sufficient for the validation of correction method. In the present study, the model test results of Terry-Fox ice breker have been used to compare the corrected results of sea trial test by varying its thickness and strength of model ice. The HSVA and ITTC methods have been applied to the present comparisions and the required power has been also validated by using the HSVA method. There are rather good agreement between the sea trial result and model test corrected by the HSVA and ITTC method. The more comparisons are expected to be carried out in near future.

해상시험 결과를 이용한 RIB의 4자유도 동력학 식별 (I) - 해상시험, 저항·추진 모델

RIB(Rigid Inflatable Boat) is widely used for coastal transportation in the commercial use and for ISR(Intelligence, Surveillance, Reconnaissance) in the military use. Since RIB is around 10 meters in length and over 30 knots in speed, its motion characteristics in waves is quite different from a large scale ship. When it turns, large roll occurs and heeling direction is opposite to the large ship's case. Currently, many countries are developing USV(Unmanned Surface Vehicle) of which type is RIB. In order to develop high performance autopilot and way point controller, it is very important to identify RIB's motion characteristics. In this paper, sea trial test results of a 7-meter RIB such as speed, turning, zig-zag, and way point control tests were represented and its resistance and propulsion model was identified by using sea trial data and Savitsky's formula. In addition, the state space model which will be used in the identification of the four-degree-of-freedom dynamics in the next step was formulated and the identification procedure was proposed.

空気潤滑システムの開発と実船試験による検証

In late years, a demand for the carbon dioxide discharge reduction from a ship and the reduction of the operation cost has been risen more and more. According to these backgrounds, the authors are grappling with establishment of the frictional resistance reduction technology of the ship by means of the air lubrication methods. In the present paper, we carried out confirmation of the air blow condition with a mock-up examination, examination at the wharf, and the numerical computation for investigation of the valve opening rate when air lubrication method is applied to large shallow water ship. After that, we confirmed the energy saving though sea trial test. When the ship was in a horizontal state we confirmed that air was blown uniformly from each small hole, by means of mock-up examination and full-scale examination by use of actual ship at wharf. In addition, through the wharf examination, we confirmed that air was almost uniformly distributed to each branch piping in heeling condition under adequate valve opening. The analytical result of the distribution of flow rate by use of MelTHERFY almost coincides with the estimated flow rate in the heeling condition. Therefore, this method is effective as an analytical technique. Thereafter, when we used air lubrication system at the speed trial test, we confirm an energy saving effect of 12% at the maximum, and the fuel consumption is reduced at the same time.

Study on the Difference of the Maneuvering Characteristics of a VLCC in Standstill from those of her in Running

The objective of this paper is to make clear the difference of maneuvering characteristics of a VLCC in standstill from those of her in running. The authors made mathematic models to calculate maneuvering motions of a VLCC in standstill using various ahead engine with full rudder angle and calculated their motions in each case and compared the calculated values with those of the same vessel running in sea trial tests. The difference of motions between them is great. For example, a VLCC in standstill can achieve a great alteration of heading over 90 degrees within the distance of 0.2L advance while she advances 3.0L for 90 degrees turning in full running sea trial turning test. Therefore whenever a VLCC in standstill meets a vessel approaching in collision course situation in near distance, it is better and recommendable that she should use her ahead engine with full rudder to avoid collision. So "maneuvering trial tests in standstill conditions" should be added to the content of sea trial tests when a newly built VLCC commence to take sea trials, that has not been included until now.

Study on the form factor and full-scale ship resistance prediction method

To consider the resistance component due to hull geometry, the International Towing Tank Conference (ITTC) adopted the resistance test method in 1978, introducing the form factor concept with two basic assumptions, i.e., the form factor of a model ship is the same as that of a full-scale ship and the form factor is independent of ship speed. However, it is not only very difficult to determine the form factor using the ITTC ’78 method, but also there have been questions regarding the basic assumptions. Therefore, the authors carried out three basic studies on the form factor concept and proposed a new extrapolation procedure for the prediction of full-scale ship resistance performance. The validity of the proposed procedure is being investigated by comparing sea trial and model test results. The results of this investigation will be presented in the near future.